The present invention relates to foamable compositions, foamed compositions and methods of making foamed compositions. In particular, the invention relates to foamable polymeric compositions including encapsulated blowing agents, foamed polymeric compositions and methods for making foamed polymeric compositions.
Conventional residential, commercial and industrial architecture commonly involve the use of structural and nonstructural components in the assembly of useful articles. These components are often made from wood. Wood can be milled into shaped structural components such as sized lumber, trim, post and beam. Additionally, wood can be used to form structural components that can be assembled with glass to form door and window units.
Lumber, trim, post, beam and assembled profiles or articles (or units) comprising wood have obvious utility and are well adapted for many uses in many residential or commercial installations. However, the wood used in these applications, under certain circumstances, can have problems. Wood can deteriorate due to the effect of fungus and insect attack. Also, wood members suffer from cost problems related to the availability of wood suitable for construction purposes. Furthermore, wood requires substantial upkeep comprising painting or staining.
Foamed thermoplastics containing wood have been used as wood replacements. For example, U.S. Pat. No. 6,054,207 discloses the use of a foamed thermoplastic such as polyvinyl chloride and wood fiber for the purpose of manufacturing high strength composite materials. See also U.S. Pat. Nos. 5,486,553, 5,539,027, 5,406,768, 5,497,594, 5,441,801 and 5,518,677. Such composites are useful in the manufacture of a structural member, such as a hollow profile, that can be used in window and door manufacture. Foamed thermoplastics are more durable and avoid the problems associated with wood. Presently, foamed thermoplastic/wood compositions are formed using various blowing agents. However, the degree of foaming in these thermoplastics presently cannot be well controlled.
It would be advantageous to provide a foamable thermoplastic composition in which the foaming may be more effectively controlled.